. >> reporter: it happens after every u.s. mass firearms tragedy. the demand for greater controls on gun. the debate gets more and more heated, only to ultimately cool down. will it be differently this time? some say yes. in a nation with an estimated 12,000 firearm related homicides each year the massacre in connecticut has touched a national nerve. it's being called a tipping point. >> i think we could be at a tipping point for two reasons. a tipping point where we might actually get something done. >> reporter: one reason is the brutality of murdering 20 children. another is the near regularity of shooting sprees. >> the public will not accept, the public will not accept as a new normal one of these incidents every month, these mass shootings. >> reporter: the newtown killings have prompted senator dianne feinstein to introduce an updated version of her assault weapons ban. >> it will ban the sale, the transfer, the importation and the possession, not retroactively, but perspectively, and it will ban the same for big clips, drugs, or strips of mo